Various floor cleaning machines are known which apply the principle of a flexible bladder or membrane to reduce the overall size and weight of the cleaning machine by using the same tank space twice with the use of a flexible and movable inner container.
U.S. Pat. No. 3,896,520 discloses a vacuum cleaner which includes a rigid vacuum-retaining outer case which acts as a clean liquid reservoir, a flaccid spent liquid-retaining container within the case, a vacuum motor for creating vacuum within the case around the flaccid container including an inlet communicating with the case. The device has means communicating with the flaccid container for drawing discharged liquid and included dirt from the surface to be cleaned into the flaccid container under the influence of vacuum, so that the container fills with used liquid at a volume rate essentially equal to the rate of depletion of the unused liquid. The used or dirty liquid is disposed of by removing the top of the machine and dumping the liquid out. The rigid vacuum-retaining outer case is an integral part of the machine and cannot be separated from the machine for cleaning or re-filling.
U.S. Pat. No. 4,196,492 discloses a carpet cleaning machine comprising a body which includes a flexible bag for holding fresh cleaning solution which is received in an external rigid storage chamber. Spent dirty cleaning solution is collected in the external rigid storage chamber. The machine carries a scrubbing unit or means for cleaning the carpet. The scrubbing means includes a nozzle means for applying fresh cleaning solution to the carpet and a vacuum means for removing the spent cleaning solution from the carpet. In U.S. Pat. No. 4,210,978, the flexible bag is replaced by a plastic membrane.
The flexible bag is permanently mounted in place and cannot be removed for cleaning of the spent dirty solution rigid storage chamber without major dis-assembly of the whole unit. Even though the bag is filled with clean water, inevitably the interior of the bag becomes contaminated with minerals and other deposits, and the exterior storage chamber becomes contaminated by dirty water. With the flexible bag being permanently mounted to both the bottom spray head outlet and to the top part of the rigid tank body, it is inevitably subject to hazardous bacterial growth without the needed access for proper cleaning of the spent dirty solution tank which is exterior to the non-removable flexible bag. The external rigid storage chamber is a permanent part of the machine itself.
U.S. Pat. No. 4,210,978 relates to a carpet cleaning machine comprising a body which carries a rigid storage chamber for holding fresh cleaning solution and a second storage chamber for receiving spent cleaning solution. A flexible membrane or partition divides an enclosed rigid cavity in the body into the first and second storage chambers. The flexible membrane is permanently affixed (ref. page 12, line 30-35) at its extremities to the rigid cavity in the body such that there is severe stress when the second chamber is full of spent liquid. The membrane is not readily removable and inevitably becomes contaminated by the dirty spent cleaning liquid. This presents the same hazardous bacterial growth problem as the previously discussed U.S. Pat. No. 4,196,492. The rigid storage chamber is not adapted to be separated from the machine.
Still further, U.S. Pat. No. 4,956,891 describes a floor cleaning machine comprising a support structure including a housing having a rigid water chamber, an inner spherical flexible container within the water chamber defining an inner chamber for retention of clean water. The spherical chamber is at the bottom permanently fixed to the spray head system outlet and at the top to the rigid tank body and thus is not adapted for ready removal from the machine. Therefore, the exterior of the flexible container and the return rigid waste tank surface becomes contaminated by dirty liquid and cannot be effectively cleaned without major disassembly of the whole unit, and thus will have the same hazardous bacterial growth problem as the previous discussed U.S. Pat. Nos., 4,196,492 and 4,210,492. The rigid water chamber is essentially integral with the machine which does not facilitate its separation from the machine.
The present invention provides a novel cleaning machine in which both the rigid vacuum retaining outer container and the inner flaccid container are adapted to be lifted as a unit from the machine and handled much as an ordinary scrub bucket for purposes of emptying, cleaning and sanitizing, and refilling with fresh cleaning liquid, followed by re-installation in the machine. This approach is very user friendly by appealing to the user who is already familiar with the use of scrub buckets.